The UEFA Disciplinary Regulations on Order and Security states: “All associations and clubs are liable for the following inappropriate behaviour on the part of their supporters and may be subject to disciplinary measures and directives.

“The use of gestures, words, objects or any other means to transmit any message that is not fit for a sports event, particularly messages that are of a political, ideological, religious or provocative nature will not be tolerated.”

Yesterday a St Johnstone spokesman said: “We’ve been fined 18,000 euros for the display of a Palestinian flag and pro-Palestine chanting at our game with Spartak Trnava by UEFA.

“Obviously it’s disappointing that this has happened but we need to see what the actual case is before commenting further.”

A Celtic spokesman said: “We have asked UEFA for written reasons regarding this decision and at this stage would not be able to comment further.”

League of Ireland side Dundalk have already vowed to challenge a similar UEFA decision to fine them £14,230 after a section of their support waved Palestinian flags at the recent Europa League tie against Croatian side Hajduk Split.

The authorities also objected to Irish fans watching the game from a standing area rather than seats in the Dundalk stadium.